1. Field of the Invention
The present invention relates to an electric horn system. More specifically, the present invention relates to an electropneumatic horn system adapted for multiple commercial uses wherein a compressed air generating unit is securely fixed within a monolithic housing during an assembly and enables multi-tonal, particularly bi-tonal sound generation, during a use. The compressed air generating unit has air venting channels to take in air for compression while reducing pressure.
2. Description of the Related Art
The related art involves generally electric and electropneumatic horn constructions and systems. Electropneumatic horns are those which generate sound by generated air flow or compressed air and are considered (very broadly due to their typical electrical operation of compressed air or air-supply valving) to be within the wider grouping of electric horns due to the electric control of the generation of the air flow or compressed air. It should be noted that electric horn constructions also include (in addition to pneumatic sound creation) the creation of electronic sound (e.g., speaker type systems) wherein sound or tone is the result of an electronic signal to a speaker and not the result of an acoustic passage. As a consequence, those of skill in the art will recognize that the use of the phrases electronic, electrical, and electropneumatic shall be considered non-limiting in the following description.
Conventionally, electropneumatic horns include acoustic units consisting of a straight exponential tube, of a length related to the frequency to be reproduced, inserted in an acoustic chamber in which a membrane, free to move with a reciprocating motion, is arranged and positioned.
Conventionally, the straight tube comprises a first stretch with generally constant cross-section, provided with an inlet mouth for the sound signal generated by the oscillating membrane and a second stretch having a section varying with a generally conical exponential layer ending with an outlet mouth for the amplified sound signal (e.g., horn shaped).
As used in these conventional electropneumatic horns, the membrane is properly stretched or positioned during a pre-assembly calibration phase by deformation against the membrane of a member referred to as a “sound generator” and applied to a chamber body, in such a way as to generate a sound with manufacturer-desired predetermined acoustic pressure during use.
In an alternatively constructed versions of the related art, the acoustic units are paired (commonly bi-tonal), and the corresponding tubes are volute wound and juxtaposed to limit the overall dimensions of the horn allowing for reduced-size installations.
As already stated, the acoustic horns, and more particularly those with a straight acoustic tube (e.g., ‘truck air horns’), are utilized in motor vehicles and are generally installed in the engine compartments and on vehicle roofs.
Acoustic horns with different features are available on the market, both by others and by the present Applicant, and are mainly classified according to the number of acoustic units, generally one to a general maximum of three tuned tonal sounds, each shaped according to the frequency that each unit should reproduce.
The need to optimize space and reduce dimensions of every element of the motor vehicle, has lead to the reduction in size of such electropneumatic acoustic horns generally, and the miniaturization of specific horn components. For example, it is known to reduce the size of the air compressor unit or member as well as reduce the overall size of the acoustic sound units.
Referring now to U.S. Pat. No. 7,038,756 to DiGiovani et al ('756), the entire contents of which are incorporated herein by reference, and FIGS. 1 and 1A (since the earlier proposed solutions had not garnered sufficient success), it has attempted to respond to the needs in the art by providing a dual tone or dual acoustic unit wherein a completed assembly 1 accommodates dual acoustic units having respective horn openings 4A and 4B within a relatively compact housing 2. In this related unit, housing 2 contains a single compressor unit, or compressor member 6 which is removably and slidably joined within an adjustable clamp to housing 2, and provides a compressed air supply via air supply outlet fixture 13 simultaneously to each acoustic unit within housing 2 via internal chambering.
As also noted, dual opposing diaphragm units 3 and 3 are shown and respectively receive, via internal chambering (not shown, but visible in the '756 patent) compressed air from compressor unit 6 via respective diaphragm air supply portals 16 and 16 (the reverse side is not shown). Diaphragm units 3 and 3, operate as sound generators and transmit the sound to the volute acoustic chambers respectively connecting each diaphragm unit 3 to respective horn openings 4A and 4B.
Compressor unit 6 consists of an operable motor housing member 14 formed from a very rigid metal body, a bottom electric brush housing member 10, wherein electrical power is received via power supply cords 5, and a top compressor labyrinth member 9. As will be noted from FIG. 1, rigid housing member 14 includes folded metal tabs 15 serving as engagement fingers joining motor housing 14 to top compressor labyrinth member 9 to prevent unintended separation and reliable operation. Typically, bottom electronic brush housing member 10 is secured to rigid housing member 14 via a plurality of removable and accessible snap-in fittings (not shown), allowing ease of assembly. Unfortunately, this ease of assembly also creates relative structural weaknesses in the overall completed assembly 1 that may serve as a source of future failure (as will be discussed).
Housing 2, includes a pair of opposing C-shaped plastic clamp arms 7A and 7B as shown for slidably and removably gripping portions of the external surface of rigid housing member 14. Additionally, an air tube member 11, having an air intake opening 12 is formed along the wall of the first clamp arm 7B and supplies air to a top air opening or inlet (not shown) in compressor to member 9. Additionally, a single mounting bracket member 17, extends rearwardly from compressor unit 6 and compressor pump member 9, allowing attachment to a weather-dry location within an inner vehicle wall mount position (not shown). As noted earlier, system 1 contains a number of relative structural weaknesses, and mounting bracket member 17 is a common location for structural failure. As can be recognized from the cantilever construction shown, mounting bracket 17 provides a single-site attachment mechanism, which tends to fail when used in high-vibration environments, including automotive and motorcycle mounting environments.
Additionally, it shall be recognized by those of skill in the art that opposing paired clamping arms 7A and 7B slidingly receive compressor unit 6, and consequently that even with air outlet fixture 13 providing an additional engagement with housing 2, the construction taught in '576 often results in mechanical failure causing separation of compressor unit 6 because there is no physical engagement between the body of the compressor unit 6 and housing 2 other than air outlet fixture 13, and, because there is no mechanism to maintain the tension between clamp arms 7A and 7B to ensure and maintain a clamping pressure, particularly during the thermal expansion common in plastic housings when employed in high temperature environments common in vehicle wall mounting positions. As a consequence of this tendency for mechanical failure, those who review the mechanical units marked with the '576 patent note the inclusion of an additional adhesive double-tape stick portion 8 between portions of clamp arm members 7A and 7B and portions of the wall surfaces of motor housing 14.
The use of such double-stick tape 8 is unfortunately also problematic since it does not address the initial structural design weakness in the engagement between housing 2 and compressor unit 6, and because such adhesive tape readily fails for a number of reasons, including: (a) degradation, melting, off-gassing, or embrittlement of the adhesive in high temp (>100 Celsius) and low temp (<O Celsius) common in standard vehicle mounting environments or (b) mechanical failure of the tape backing structure itself. Since the related art recognizes the preferred use of unit 1 within the automotive engine cavity, where temperatures routinely exceed 100 Celsius, this thermal and mechanical weakness has resulted in unacceptable failure rates. Since the related art also recognizes the preferred use of unit 1 within the marina and water environments, where chemical reaction with the enhanced humidity and corrosive environment attacks adhesives, this material degradation has resulted in a similarly unacceptable failure rate.
As an additional detriment of the conventional construction discussed, while internal splash baffles (not shown) are discussed in '576 within air intake tube 11, it will be recognized that horn openings 4A and 4B are on the same level with air opening 12 for the compressor air intake, and are not similarly protected from the impact such rigid baffles would have on sound tone and overall sound quality. Therefore, while water penetration within the acoustic tubes via respective horn openings 4A and 4B is no less a danger then water penetration to air inlet tube 11, the related art has not recognized this detriment and has similarly not provided a solution. Consequently, while water-splashing and moisture may readily damage unit 1 via entry to horn openings 4A and 4B even while the unit is within a contained environment, for example an automotive engine cavity, there is an unsatisfied need for substantive improvements in weather and water resistance recognized within the related art. Therefore, there is a need for a weather resistant solution that has minimal or no impact on the generated tonal or sound quality.
Additionally of concern are circumstances wherein the unit is employed as a full replacement for an originally-manufactured horn for a vehicle. Where full replacement use occurs, consumers have no other alternative for emergency use, and consequently the horn must operate at the highest levels of reliability and safety.
What is not appreciated by the prior art therefore, is the need for an improved system comprising a compressor unit and housing member that avoids at least one of the detriments noted earlier so as to provide improved unit operational reliability, as well as operability, minimize mechanical and thermal failures within a wide field of user environments.
Accordingly, there is a need for an improved electric horn system, and more specifically and improved electropneumatic horn system that responds to one of detriments noted above.